解
-4x²+(2x-3y)²
=(2x-3y)²-(2x)²
=(2x-3y-2x)(2x-3y+2x)
=-3y(4x-3y)
16(a+b)²-9(a-b)²
=[4(a+b)]²-[3(a-b)]²
=[4(a+b)-3(a-b)][4(a+b)+3(a-b)]
=(a+7b)(7a+b)
9m²(a-b)³+49(b-a)³
=9m²(a-b)³-49(a-b)³
=(a-b)³[(3m)²-7²]
=(a-b)³(3m-7)(3m+7)
(x+y-z)²-(x-y+z)²
=[(x+y-z)-(x-y+z)][(x+y-z)+(x-y+z)]
=(2y-2z)(2x)
=4x(y-z)
(a²-b²)+(3a+3b)
=(a-b)(a+b)+3(a+b)
=(a+b)(a-b+3)
x^4-1
=(x²)²-1²
=(x²-1)(x²+1)
=(x-1)(x+1)(x²+1)